sw XHTML export: fix handling of character styles

Namespace prefix was missing here.

Change-Id: Id746d47713b22e2efd5d679c2325b32a0bee8a09
Reviewed-on: https://gerrit.libreoffice.org/51270Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>

sw/qa/extras/htmlexport/data/reqif-p.xhtml

@@ -2,3 +2,4 @@
 <reqif-xhtml:table><reqif-xhtml:tr><reqif-xhtml:td>in table</reqif-xhtml:tr></reqif-xhtml:tr></reqif-xhtml:table>
 <reqif-xhtml:a href="http://libreoffice.org/">http://libreoffice.org</reqif-xhtml:a>
 <reqif-xhtml:span style="text-decoration: underline">u</reqif-xhtml:span>
+<reqif-xhtml:strong>s</reqif-xhtml:strong>

sw/qa/extras/htmlexport/htmlexport.cxx

@@ -357,6 +357,9 @@ DECLARE_HTMLEXPORT_TEST(testReqIfParagraph, "reqif-p.xhtml")
 
     // This was "<u>" instead of CSS.
     CPPUNIT_ASSERT(aStream.indexOf("<reqif-xhtml:span style=\"text-decoration: underline\"") != -1);
+
+    // This was <strong>, namespace prefix was missing.
+    CPPUNIT_ASSERT(aStream.indexOf("<reqif-xhtml:strong>") != -1);
 }
 
 DECLARE_HTMLEXPORT_ROUNDTRIP_TEST(testReqIfOleData, "reqif-ole-data.xhtml")

sw/source/filter/html/htmlatr.cxx

@@ -3049,7 +3049,7 @@ static Writer& OutHTML_SwTextCharFormat( Writer& rWrt, const SfxPoolItem& rHt )
 
     if( rHTMLWrt.m_bTagOn )
     {
-        OString sOut = "<";
+        OString sOut = "<" + rHTMLWrt.GetNamespace();
         if( !pFormatInfo->aToken.isEmpty() )
             sOut += pFormatInfo->aToken;
         else